An aircraft gas turbine engine includes rotary mechanical devices such as vanes and rotary fuel valves. To control the operation of such an engine by an electronic control unit, it is necessary to electronically monitor the angular position of these devices. If a microprocessor is utilized as the engine control "brain", an angle sensing mechanism with a digital output may be interfaced directly to the microprocessor. A resolver with relatively rotatable coils may be used as the analog angle sensor. However, short and open circuit conditions of the resolver terminals can cause the associated resolver processor to produce misleading angle indications. These midleading angle indications may have a detrimental effect on the control of the engine. Therefore, an angle measuring circuit which has the capability of recognizing fault conditions of the resolver terminals is desired.